Copper base friction material with dispersed spinels



D. J. ROTH Feb. 18, 1969 Original Filed Oct. 15, 1965 Sheet WE'AE i SPINEL. CONTENT TI I .Z

WEAQ

8 SPINEL CONTENT WEIGHT PERCENT \S'PINEL.

3 2 au 76 m w w w wwmw o o. o. o ow.

WEIGHT PERCENT SPINEL.

JNVENTOR. Douc LAS J. BOTH ATTORNEY Feb. 18, 1969 I D, J, ROTH 3,428,440

COPPER BASE FRICTION MATERIAL WITH DISPERSED SPINELS Original Filed Oct. 15. 1965 Sheet 3 of 2 WEAR LL2 SPINEL CONTENT g0 .0008 D 0007K f; .0000 g: .0005 g .0004 x E 3 -fig- .000 m 2 2 .0001

5 i It) I? 20 WEIGHT PERCENT SPflNEL INVENTOR. DOUGLAS J. Eon-1 BY ATTORNEY United States Patent 3,428,440 COPPER BASE FRICTION MATERIAL WITH DISPERSED SPINELS Douglas J. Roth, South Bend, Ind., assignor to The Bendix Corporation, a corporation of Delaware Continuation of application Ser. No. 496,278, Oct. 15, 1965. This application Nov. 21, 1967, Ser. No. 684,840

U.S. Cl. 29-1825 4 Claims Int. Cl. B22f 3/00, 5/00 ABSTRACT OF THE DISCLOSURE A sintered copper base inorganic friction material having less than about 25% by weight of a spinel disbursed throughout. The spinel additives are preferably chromate and aluminate spinels such as magnesium aluminate, magnesium chromate, or nickel chromate which, when added in the quantities indicated, produce a marked reduction in friction material wear.

The present invention is a continuation of my co-pending application Ser. No. 496,278, filed Oct. 15, 1965, and now abandoned.

It is an object of the present invention to provide an inorganic friction material having a copper base or matrix with improved wear characteristic compared to prior art copper base lining under similar load conditions.

It is another object of the present invention to provide a copper base friction material having a powdered spinel added in small quantities which greatly enchances wear properties.

Other objects and advantages of the present invention will become apparent with reference to the accompanying description and drawings wherein:

FIGURES 1, 2 and 3 illustrate graphs of the wear characteristic of copper base linings of various compositions with and without spinel additions.

For purposes of practicing this invention, a spinel is consist of a sintered copper base material with a ceramic added to enhance friction and graphite for lubrication. Other metal additives in small quantities are often present to reduce chatter, noise and improve lining strength. While such additives are contemplated to be used in the present invention to obtain an optimum lining, they are not essential in its practice.

Data has been prepared and set forth in the tables below which serve to describe the present invention. All lining materials were fabricated by identical methods using conventional powder metallurgy techniques involving mixing, compacting, sintering and coining. The lining material was fabricated into cups which were then riveted to AMS 6385 steel backing plates (stators). However, it will be apparent to those skilled in the art that lining shape and attachment are not critical and other means maybe employed in its attachment.

The stator plates with mounted lining were then placed on a single surface dynamometer using 12%" diameter rotors and stators and subjected to friction stops under the following energy conditions:

Test-s In- Table I Tables II-VI Table VII Lining Area Loading (ft. lbs./

in. 18,550 14, 050 7,025 Rotor Mass Loading (tt.1bs./

1b. 162, 800 88, 400 44, 200 Primary Heat Sink Loading ([13. lbs/lb.) 103, 800 66, 000 33,000 Stop Time (seconds) 22. 5 17. 5 15.0

The energy conditions selected are comparable to loadings in aircraft brakes. The lightest loading representing normal landing brake energies encountered in service and the greater loading represent more severe conditions such as encountered during maximum gross Weight landing conditions.

In Table I below, there are set forth the results of nine tests under the most severe loading condition of a copper base lining of a composition as listed in the table.

TABLE I Lining Composition (Weight Percent) Cu Mo Steel Mullite SiOa Graphite Spinel W/S/S Fiber MgO-AlaOa NOTE.Th0 above linings were all compacted at 40,000 p.s.i., sintered at 1,800 F. in

Exothermic Gas and coined at 100,000 p.s.i.

a precise combination of a divalent metal oxide (monoxide) and a trivalent metal oxide (sesquioxide) arranged according to the general formula MO-M O (or MM O where each M may represent the same or a different metal. The monoxide and sesquioxide are combined in a face centered cubic array of oxygen ions with divalent cations in one-eighth /s) of the tetrahedral vacancy positions and trivalent cations in one-half /2) of the octahedral vacancy positions. Further description of spinels may be found in W. D. Kingery, Introduction to Ceramics, pages 115-116; Gray et al., The Defect Solid State, pages 201-203, and Wyckotf, Crystal Structures, Chapter VIII, pages 16-17.

Inorganic friction materials, while having some applica-bility to the ground vehicle field, particularly heavy duty, are primarily useful as friction linings in heavyduty aircraft brakes where the high kinetic energy and high heat generated require a metal base friction material. Copper base linings are in Wide current use and generally The spinel content, MgO-Al o was varied from 0 to a maximum of 20% by weight. After every tenth stop, the friction material was measured and its wear recorded. The total wear at the end of the test is divided by the number of stops and the number of surfaces to give an average reading of Wear per surface per stop. This wear termed wear/surface/stop (W/S/ S) is entered in the extreme right column and shows a wear reduction for even very minute spinel additions. Test points one through eight are plotted in FIGURE 1. The greatest wear reduction was obtained with 10% spinel, Test Number 7, and no further reduction was obtained for greater spinel additions. It will be understood that this does not preclude the addition of spinel in quantities greater than 10% and, in fact, from 10 to 20% represents a good processing range wherein extremely repetitive wear results can be obtained even though one does not take great care in controlling the percentage of spinel addition. Beyond 25% spinel addition, it becomes unenergy loadings of a copper base lining having lead and economic to add greater spinel quantities and the abrasive tin additives, and is illustrated below. and dispersion hardening effects of spinel predominate. Two different particle sizes of magnesium aluminate Thus, the ultimate upper limit of spinel addition may be spinel, 40 and 200 mesh, were tested, both showing considered 25% by weight. It will be noted that in test improved wear demonstrating that particle size is not points one through eight, spinel has been substituted for 5 critical. Two other spinels, magnesium chromate and the mullite content. Mullite is a ceramic additive for connickel chromate, were also tested, both showing comtrolling friction level; however, this function, in addition parable reduced wear showing that it is the spinelstructo wear reduction, may be accomplished by the spinel ture rather than specific spinel type that produces the and it is not essential in the practice of the present inreduction in wear rate. Test points 10 through 15 of Table vention to include a ceramic when significant percentages 10 II are plotted in FIGURE 2.

TABLE II Lining Composition (Weight Percent) Test No. W/S/S Cu Sn Mo Pb Steel Mullite Graphite 40 Mesh -200 Mesh MgO-CrzOa NiO-Cr O Fiber MgO-AlzO; MgO-AlzO;

No'rE.The above linings were all compacted at 40,000 p.s.i., Sintered at 1,400 F. in Exothermic Gas and coined at 100,000 p.s.i. of spinel are present. In all tests recorded herein, the Tables III, IV, V, VI and VII compile additional data coefficient of friction of copper base lining with spinel run recording reduced wear rate of copper base lining added has been maintained at an acceptable level. For with spinel added.

TABLE III Lining Composition (Weight Percent) Test N0. WIS/S Copper Mo Sb Monel Steel Mullite Graphite 40 Mesh 200 Mesh Fiber lwgo-Alzos MgO-AlgO;

1No'rE.1he above linings were all compacted at 100,000 p.s.i., sintered at 1,800 F. in Exothermic Gas and coined at 100,000 ILS. linings normally having a low coeificient, spinel additions 40 TABLE Iv cause no appreciable change whereas a moderate de- L, C H W mp t crease has been observed in lining normally having a TeStNo mmg ompos 61g men) w/S/s high coefficient of friction. This latter decrease is con- C11 Mullite Graphite 5 5 sidered within acceptable limits and the friction level can g z 3 be improved, if desired, by greater ceramic additions. 13-8 18.? .ggg a Table II contains similar data obtained on intermediate 0 TABLE V Lining Composition (Weight Percent) Test No. W/S/S Cu Mo Steel Mullite Graphite 40 Mesh MgO-CrgO; NiO-CraOa Fiber MgO-AlzO Nora-The above linings were all compacted at 40,000 p.s.i., sintered at 1,800 F. in Exothermie Gas and coined at 100,000 p.s.i.

TABLE VI Lining Composition (Weight percent) Test N0. WIS/S Cu Mo Sb Moncl Steel Mullite Graphite 40 Mesh -200 Mesh MgO-CnO; N iO-Cr O Fiber MgO A1103 MgO -Al203 NorE.The above linings were all compacted at 100,000 p.s.i., sintered at 1,800 F. in Exothermic Gas and coined at 100,000 p.s.i.

Norm-The above linings were compacted at 40,000 p.s.i., sintered at 1,800 F. in Exothermie Gas and coined at 100,000 p.s.i.

Table III data duplicates the results of Table II data with respect to a Monel containing copper base lining. Test points through 22 are used to plot FIGURE 3.

The composition in Table IV, all metal additives, were deleted and copper content increased to 75%. The comparison between wear rates in the control sample of test point 24 and the spinel containing test point 25 demonstrates a striking wear reduction.

In Table V, the tests utilize a copper base lining with 5% by weight additions of three different spinels. All three provided marked improvement in the wear rate. It will be noted that in this case the spinel additions replaced copper and mullite was maintained at a high value Of 25% throughout.

In Table VI the tests utilized a copper base lining having metallic additives of molybdenum, steel fiber, antimony and Monel. Additions of 5% by weight of three different spinels, one of which was utilized in two different particle sizes, were made. All four linings containing spinel showed a marked improvement in wear over the lining containing no spinel. In this case, the spinel additions replaced mullite.

The two tests recorded in Table VII were run at the lowest energy conditions comparable to that encountered in normal aircraft landing conditions (exclusive of emergency stops). The addition of 5% spinel significantly reduced wear, indicating the improved wear advantages of the present invention may be obtained at all energy conditions and greater lining life can be expected under all conditions.

I claim:

1. A friction material comprised of a sintered copper base having dispersed therein less than about 25% by 6 weight of a spinel and less than about 15% by weight of graphite.

2. A friction material comprised of a sintered copper base having dispersed therein from 0.2 to 25% by weight of a spinel and less than about 15 by weight of graphite.

3. A friction material comprised of a sintered copper base having dispersed therein less than about 15% by weight of graphite and from 0.2 to 2.5% by weight of a spinel selected from the groups consisting of chromate spinels, aluminate spinels or mixtures thereof.

4-. A friction material comprised of a sintered copper base having dispersed therein less than about 15% by weight of graphite and from 0.2 1110 25% by weight of a spinel selected from the groups consisting of magnesium aluminate, magnesium chromate, nickel chromate and mixtures thereof.

References Cited UNITED STATES PATENTS 2,784,105 3/1957 Stedman 29-1825 2,818,634 1/1958 Batchelor 29-1825 2,922,221 1/1960 Morton 29-1825 2,966,737 1/1961 Spokes 29-1825 3,019,103 1/1962 Alexander -206 3,114,197 12/1963 Du Bonis 29-1825 X 3,320,036 5/1967 Scruggs 75-206 X 3,320,037 5/1967 Scruggs 75-206 X CARL D. QUARFORTH, Primary Examiner.

A. I. STEINER, Assistant Examiner.

US Cl. X.R. 73-206 

